Artificial shellac and process of making the same



July 15, 1930. A. w. BURWELL 1,770,876

ARTIFICIAL SHELLAC AND PROCESS OF MAKING THE SAME Original Filed Dec. 20. 1925 gwoentw M4 1. 6M

v ZJ- ratented July 15, 1930 UNITED STATES PATENT OFFICE ARTHUR W. BUBWELL, OF NIAGARA FALLS, NEW YORK, ASSIGNOR TO ALOX CHEMICAL CORPORATION, OF NEW YORK, N. Y., A CORPORATION 01' NEW YORK ARTIFICIAL SHELLAC AND PROCESS OF MAKING THE SAME Original application filed December 20, 1826, Serial No. 156,052, and in Great Britain October 6, 1927. Divided and this applicaton filed January 12, 1928. Serial No. 246,096.

' the hydrocarbon mixture.

An object of the present invention is to provide petroleum ydrocarbon oxidation products which consist essentially of saponifiable, water-insoluble hydroxy-carboxylic acids insoluble in petroleum hydrocarbon mixtures. More specifically, the present invention concerns the shellac-like products obtained by the controlled oxidation of mid continent or Pennsylvania petroleum distillates havinga density of from about 40 to about 36 Baum, i. e., the so-ealled fuel oil distillates, although I have found that these products are obtainable from other petroleum distillates than those just mentioned, such as,

- for example the distillates having a density of 33 to 18 Baum.

The process of making these shellac-like products consists generally in the liquid phase oxidation of hydrocarbons or mixtures thereof, under such conditions as to promote the formation of sa onifiable, water-insoluble,petroleum-insolu le hydroxy-carboxylie acidsand the isolation of the said acids from the partially oxidized mass.

Although this invention is not restricted to the use of any particular hydrocarbon or mixture of hydrocarbons, I prefer to use as starting material the lowest cost petroleum distillate obtainable. For example, the so-called fuel oil distillate having a densit of 4036 Baum, has been found to be a vantageous due to its relatively low cost; In general, it may be stated that the proneness to form petroleum-insoluble hydroxy-carboxylic acids is vparticularly inherent in those petroleum hydrocarbon mixtures which are of relatively higher specific gravity and which contain a minimum of crystallizable bodies (e. g. wax).

The invention will be described and illustrated hereinafter b reference to a batch process, it being un erstood, however, that the procedure may be made continuous, as shall be explained.

In the accompanying drawing there is shown diagrammatically one form of apparatus suitable for use in carrying out the process of the invention.

The oxidation step proper takes place in an upright. cylindrical reaction vessel or oxidizer 1, which may be, for example, about 5 feet in diameter and about 16 to 18 feet in height. The oxidizer 1 ma be made of any suitable material such as-iron or steel and should be capable of withstanding pressures up to 350 pounds per s uare inch. Preferably, the oxidizer 1 shoul be made of or lined with material which is resistant to the corrosive action of the reaction mixture; for example, provided with an inner shell of aluminum 2. The oxidizer is provided at a point near its lower end with a tight coil 3 which serves as a heating or cooling coil as required. Suitable means, not illustrated, such as a jacket surrounding the oxidizer, also may be used to control the tem 'erature of the oxidation reaction. At a point between the lower end of the oxidizer 1 and the tight coil 3 is an air spray pipe 4 connected by pipe line 5 to an air compressor 6. .-Air spraypipe 4 is so designed that air is ejected from it in the form of fine bubbles. 7, 8 and 9 are valved hydrocarbon supply pi e, a valved liquid discharge pipe and a valve gas discharge pipe, respec tively. 10 is a pressure gauge, and 11 IS 9.

thermometer. 12 isa separating tank fed by the valved liquid discharge pipe 8' leading steam, or the like, to the still 17. 23 is a valved conduit for thetransference of distillate from the distillate receiver 19 to the valved conduit 14'. 24 is a swing suction or decantation device in separating tank 12.

The process is carried out in the apparatus illustrated as follows:

A petroleum hydrocarbon mixture, such as, for example, the 4036 Baum fuel oil distillate above mentioned, is charged into the oxidizer 1, a small amount of an oxidizing catalyst or exciter of'oxidation, such as a compound of manganese copper or iron,- say manganese oleate,-amounting to about 0.1 percent of the weight of the oil is added and the mixture heated up to a temperature in the neighborhood of 120 C. or higher, preferably to about 135-140 C., and an oxidizing gas, preferably air, is supplied through the sp ay pipe 4. Gases are permitted to accumulate in the oxidizer until the desired pressure is reached, after which the pressure is maintained or regulated by controlling the discharge of gases through the valved gas discharge pipe 9. The pressure may vary considerably, say from 150 to 350 pounds per square inch. The preferred pressure will depend upon a number ofconditions, including the temperature maintained, the kind of hydrocarbon mixture under treatment, the rate of air supply and, if oxygen-enriched air is used, upon the richness of the oxygen supply. It is preferred to carry out the oxidation process under such conditions that thereaction is substantially self-sustaining. In general, the reaction is self-sustaining at a temperature of about '135140 C., and at a pressure of about 250 pounds per square inch, with the hydrocaron under treatment, although temperatures and pressures may vary between wide limits. Thus, for example, oxidation has been observed at a temperature as low as 100 Ca; it is more rapid above 120 C., and the temperature may be allowed to rise to 155 C.

with satisfactory results under some circumstances. Therefore, while I prefer to carry out the oxidation process, at a temperature at which the reaction rate is'fairly rapid, say

.takes place.

During the oxidizing treatment, as is stated above, gases collecting in the upper end of oxidizer 1 are released through the pipe 9. These gases contain practically no oxygen, but do contain carbon dioxide, nitrogen and varying quantities of volatile acids, ketones and other products of the oxidation. The volatile acids, ketones and other products may be condensed in a suitable condenser (not shown) and further treated for the recovery of formic acid, mixed light ketones, etc.

During the course of the treatment of the petroleum distillate in the oxidizer 1, there appear to be formed, during the earliest stages of oxidation, formic acid and high molecular weight ketonie and/or aldehydic bodies; continued oxidation results in the production of saponifiable water-insoluble carboxylic acids having molecular weights approximately one and one-half times those which would naturally be calculated for acids derived from the original (i. e., unoxidized) hydrocarbons. Prolonged oxidation converts these petroleum-soluble carboxylic acids into petroleum-insoluble hydroxy-carboxylic acids having about the same, or lower, molecular weights as those which would naturally be calculated for acids derived from the original hydrocarbons, low molecular weight ketonic and/or aldehydic bodies, water, and additional amounts of formic acid.

For the purposes of the invention, it is de sirable to continue the oxidation treatment until the maximum amount of the etroleum-insoluble hydroxy-carboxylic aci s has been obtained while avoiding undue decomposition of the hydrocarbons, as evidenced by an excessive amount of carbon dioxide in the etlluent gases and Vapors passing to the condenser through the valved gas discharge pipe 9. Usually this occurs when the mass in the oxidizer 1 contains from 25-35% of petroleum-insoluble matter. At this point, which may be determined either by observing a sample of the mass from the oxidizer. by titration, or by observations as to the time and rate of How of the air for a given quantity of starting material and the undue increase in the relative amount of carbon dioxide in the eiiluent gases, the reaction mixture in the oxidizer 1 is discharged through the valved liquid discharge pipe 8 into the separating tank 12.

Upon settling, thereaction mixture separates into three layers. The bottom layer is found to consist of a strongly acid, aqueous solution of water-soluble acids together with some unsaponifiable matter which is soluble in this strong solution. This layer is drawn off, through the valved conduit 14, into the acid water tank 21-. The intermediate layer consists essentially of hydroxy-carboxylic acids which are insoluble in the reaction mixa fresh charge of the distillate containing the Hate s liit i. y Which it is SRPOnifiQd to form ture, and the top layer is found to be a mixthe distillate receiver 19. The latter distiltui'e comprising unoxidized petroleum, peate contains volatile, esterifiable acids of troleum-sollible earboxylic acids, some by lower molecular weight which maybeworked droxy-carboxylic acids, and primary oxidaup for the recovery of Values contained tion products, such as, for example, ketonic therein,-e. g. for the manufacture of and/or aldehydic compounds, primary and csters,-and heavier carboxylic acids which secondary alcohols, ethers, and possibly ome may be returned to the oxidation cycle esters. through the valved conduits 23 and 14' for After the settling has proceeded to the conversion into hydroxy-carboxylic acids. point where the supernatant oil is perfectly t is noted that the carboxylic acids readily clear. the said top layer carefully is withare converted into resin-like products, Which drawn iv means of the swing suction 24, c iai'acteristic apparently is due to the ease trausfei'ied through the valved conduit 14' to with which said acids polymerize. the petroleum distillate supply tank 15, and The residue in the still 17, obtained by the t lere mixed with fresh distillate in the precarrying out of the above-described proferred proportions of2:1 for use in charging FPdHPP 1'S the shenaclike Prodlwt whlch i the oxidizer for a subsequent oxidation treathe basis of the invention. In general, it ment. {aid mixture, consisting of fresh disrang in c l r from am er t0 k r stillate and material which has already been lly, the lighter the starting material (1. subjected to oxidation treatment, does iiot rethe H X d Petroleum hydrocarbon quire thepresence of an oxidizing catalyst or mixture) the lighter the color of the end exciter of oxidation to etl'ect normal oxidaproduct. T e product, apparently an ac d, tion, the reaction proceeding in a manner or acid anhydride body. is readily soluble in identical to that observable upon oxidiZin Warm caustic soda solution or sodium carboadded cxciter of OXldfltlOIl. soaps very similar to the soap produced by lhe residue int e separating tank 12, comthe saponification of natural shellac. It iS prising saponifiable, petroleum-insolubl insoluble in petroleum, in the fatty Oils, and Wa er-insoluble, hydroXy-carboxylie id i other similar oils, but is soluble in carbon tien repeatedly washed with small uantitetrachloridel tl "P t P l ties of water, which may be caused to rise to tions maintained during the vacuum distillathe top or settle to the bottom by appropriate tion operation, it ranges in consistency from control of the conditions. The wash water is a hard. brittle, readily grindable solid to 8. found to contain some Water-soluble comrelatively softer, tacky product. The pounds, and therefore preferably is trans- Softer, tackv varieties are solublein alcohol The water-free hydroxy-carboxylic acids he chief characteristic of this product, are transferred from the separating tank 12. from an economic viewpoint, is its high dithrough the valved conduit 13, into the still electric property. l7 and are there subjected to a vacuum distil- In order to arrive at a comparison of the ation treatment for the removal of substanrelative dielectric properties of natural sheltially all of those components which w uld lac and of the shellac-like product of the present invention. alcoholic solutions of the the atmosphere over protracted periods of two substances were prepared by dissolving no time. The specific conditions under which 55 grams of each in 67 grams of alcohol. the distillation is conducted depend lai'gelv Sheets of common writing paper, averaging upon the desired physical character of the 0.0033 inch in thickness. were coated or imend product. but in general the operation pregnated with the solutions and then al- 10-20 m. m. of mercury and at as low a tembeing of four thicknesses of the impregnated perature as possible for the substantially com and dried paper were prepared and their plete removal of volatilizable compounds,-e relative thicknesses in inches ascertained to g. from 140 to about 275 C. The relatively be:

Test piece using natural shellac l. g: 0458 lower temperatures. with correspondingly in- Test piece using synthetic shellac 3:823, M39 of relatively softer and less brittle products. an .1 thickness 0f 012417 1.11011 he volatilized material passing off from the t 9 case of the test Pieces natural still 17 und r th infl f th rtial shellac, and 0.0391 inch in the case of the vacuum maintained by the vacuum pump 20, test pieces using synthetic shellac.

and, preferably, assisted by a stream of air The dielectric capacities of these test or steam admitted by the valved conduit 17, pieces were ascertained on a test transformer are condensed in condenser 18 and caught in having as one electrode a brass bar inch in diameter and the test piece. were checks of four-thic uncoated or The following v Dtlll'ClTtC capacity,

Test pieces Uniinpregnated paper test pieces...

It should be noted that the synthetic thinner in cm ural shellac, electric capacit The tests (1 synthetic she the natural oint than The above Average single Inch 0. 0033 Inch 0.0417 0.0391 3.354

The shellac-like p adaptable tions in w ple, it may bestos, mica, tci'ials in t same prop mixture su temperatur tomarily emp compositio shellac. which i wood.

In su may be p 75-65% 0 of wood pu product. those just me against the di kness test pie unimpregna Test pieces using the synthetic shellac ol' the presen using natural shellac-..

that of nat tests are suinm duction, under he resulting 5 hard, dense be sawed, worked in the sa bstantially t built up of ted paper.

re obtained:

measured in kilovolts wood pulp, or othe ame manner, ortions in which for the pro tempera tioii. artificial lumber,

generally For example, the hard, b

about 10 parts by Weight of -like prod and thorough weight of wo the same for the pro sulation molded compo d homogeneous, turned and me manner as a natur be same lded art ntioned, as well inted at the end ame time th test pieces using somewhat than those using nathave a higher di- Th the latter.

the f stickier higher melting lac.

arized as follows:

although Average thickness Kilovolts x-flovoufs dielectric ated capacity test piece thickness of unimgun com rising roduct above des n all insulation hicli shellac is used be admixed with manner, there icles containing of mica, or 50% said shellac-like ed compositions such as as in the coinadjacent e results ct that the than or examwood flour, asr inert maand in about the shellac is used, conditions 0 of molded insulaand molded products uct are d with about duction of a containing P sition may general y al hard e uct adva position above example involving the use of woo electric capacity flour, I have found that the shellac-like prodntageously may be used in t e form forming the subject matter of the of a salt,as, for example, the calcium salt, of the petroleum-insoluble hydroxy-carboxylic acids, in which form the product readily may be ground and admixed with the inert materials.

Also, it may be introduced, in finely divided condition, into paper pulp in the beating engine, for the roduction of a stiff, hard aper having high dielectric properties. In M the form of a sticky, highly viscous product it may be used for the impregnation of tape for electric insulation, pro ucing thereby a highly dielectric tacky tape which sticks well to the wire or to itsel e shellac-like product, hereinbefore described, may be dissolved in suitable solvents to the production of a solution adaptable for use as a substitute for the commonly used solutions of natural shellac.

It is noted that the hard, brittle, shellaclike product above described may be preared by merely exposing1 the petroleum-inis to be understood that the invention is not restricted thereto, and that the rocess 0 making said product might well carrie out by recourse to a continuous or cyclic procedure, involving the controlled oxidation of high a movin body of oil, continuous separation of the petroleum-insoluble hydroxy-carboxylic acids from the reaction mixture, and continuous return of unoxidized oil and partial oxidation products to the oxidizer.

fi \Vhile the production of the hereinbefore described shellac-like produce is not restrictth ed to any particular theory of oxidation reacf tions, the following is advanced as being a robable explanation of said reactions:

In regard to the reactions which may ta e lace during the controlled oxidation of petroleum hydrocarbon mixtures by means 0 air under pressure at reacting temperatures, it is thought that the main primary reaction is one in which the oxygen attaches itself to a secondary carbon atom in the hydrocarbon chain and, in general, it is believed that the first secondary carbon atom after the primary carbon atom,-in other words the carbon atom in the /3-position to the CH, group at the end of any chain or branch,- -is the one to which the oxygen first attaches itself. It

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the fact that is the opinion, from many observations, that the oxygen is absorbed without the loss of any hydrogen; in other words, a hydroxyl group is formed at this point, thus forming a secondary alcohol. A

The principal reason for assuming that this is the case is the fact that with the oxidation of a given mass of petroleum there is obtained as high as 15% of formic acid and it is believed that this is due to the end hydrocarbon radical being eliminated in the form of formic acid by the oxidation. of a ketone formed from the secondary alcohol in which the hydroxyl is attached to the B carbon atom. The above conclusion is supported by oxidized it first forms a ketone. When a ketone which is a methyl X ketone that is, one in which the methyl group is onone side of the CO group and a roup of very much higher molecular weight is on the other side of the CO group,-such ketone oxidizes in such manner as to leave the group attached to the larger molecule, the CO group thus becoming the carboxylic group of the high molecular weight acids and the CH8 group forming other words is that when ketone are oxidized the CO group attaches itself to the radical of higher molecular weight and the roup of lower molecular weight is oxidized to the corresponding acid containing only the total number of carbon atoms which that group has minus the CO group.

Thisview is further sup orted by the fact that of the oil remaining ater removal of all easily volatile and all acid products the greater proportion forms crystalline compounds with bisulphite, indicating the pres ence of rather large amounts of ketones or aldehydes but, as before stated, the opinion inclines to the formationof ketones rather than aldehydes because of the very large production of formic acid. When it is considered that one is treating hydrocarbons with an average composition around (L H, and that one obtains as high as of actual formic acid there seems to be almost no other explanation for the main or principal reaction. It has been found also that the mixture of acids produced under conditions tending to avoid shows a molecular weight which, in most cases, corresponds to hydrocarbons of about b0% higher molecular wei ht than those chosen for the oxidation. 'Ehis may be accounted for in two possible ways. There may be incipient oxidation in the end hydrocarbons,that is, of the methyl group of the hydrocarbons,'in such a way as to efi'ect what is known as the Kolbe reaction. If simultaneously, hydrocarbon molecules are so oxidized that the methyl group, in the case of each molecule, loses one hydrogen atom, one would when a secondary alcohol 'is' formic acid. The rule in.

- .lic acids.

production of hydroxy-acids' by an atom of oxygen, two

have a synthesis immediately of the two hydrocarbon molecules forming one of twice the molecular weight less two hydrogen atoms. The other possible explanation, which would appear to be the stronger, is as follows: The acids when first formed are extremely liable to further oxidation and as in practically all cases one would have at the other end of a straight chain, or at any other branch, a carbon atom in relatively the same position as the first secondary carbon atom which had been oxidized to ketone and acid which also would be oxidized, probably almost simultaneously, to an alcohol. The acid in one case would either form a lactone with itself or would form an ester with the alcohol at the other end of the same chain in another molecule of the same or other acid, thus forming an ester-acid and, as the acids of lower molecular weight are frequently much more active in ester formation than those of higher molecularweight, it is probable that there would be a synthesis of this kind producing an average molecular weight of about 50% higher value than the simple acid theory would account for.

lt seems proper to infer, from the above theory, tl1at the oxidation reactions occur in such manner that very large molecules are formed by the esterification of hydroxy-acids by acids of the same, or higher, or lower, molecular weight, thus forming almost endless chains. Separations by partial precipitation -.have obtained from acids which show an average molecular weight of about 360, acids having molecular weights as high as 800 and, from the same'mixture, there have been precipitated acids having molecular weights as low as 100. a This is particularly true where the oxidation has been carried far enough to form petroleum-insoluble hydroxy-carboxy- This would very naturally be the case since it is just these acids which we know are the hydroxy-acids-as they show a considerable absorption of acetyl and we havenow proof of their polymerization either through esterization or through polymerization due to the fact that they have the hydroxy group. This hydroxy group also may readily become a ketone group, as is readily perceivable. Ketones in themselves are also extremely active; especially, the higher ketones show a great tendency to polymerize. This may be an added cause for the production of acids of extremely high molecular weight.

An additional fact which supports the idea of ester acids or ketone acids being formed is that, if these higher molecular weight acids are distilled without too much destruction, there are obtained mixtures of lower molecular'weight acids and ketones with some molecular weight. This would appear to support the ester acids hypothesis.

This application is a division of my copending application Serial No. 156,052, filed Dec. 20, 1926.

I claim:

1. A molded article comprising inert filler and a material comprising saponifiable, water-insoluble, petroleum-insoluble hydroxy-carboxylic acids obtained by contacting a free-oxygen containing-gas with a petroleum hydrocarbon mixture m-li uid state at a reactive temperature of from a cut 100 C. to about 155 (1., and at a pressure greater than atmospheric, producing thereby saponifiable, water-insoluble, petroleum-insoluble hydroxy-carboxylic acids, separating the said acids from the reaction mixture, and subjecting the separated acids to vacuum distillation.

2. A molded article comprising about parts by weight of wood flour and about 10 parts by weight of a material comprising saponifiable, water-insoluble, petroleum-insoluble hydroxy-carboxylic acids obtained by contacting a free-oxygen containing gas with a petroleum hydrocarbon mixture in. liquid state at a reactive temperature of from about C. to about C. and at a pressure greater than atmospheric, producing thereby saponifiable, water-insoluble, etroleum-insoluble hydroxy-carboxylic aci s, separating the said acids from the reaction mixture and subjecting the separated acids to vacuum distillation.

In testimony whereof, I afiix my signature.

ARTHUR W. BURWELL. 

